Relative importance of soil physico-chemical characteristics and plant species identity to the determination of soil microbial community structure

• Weeds and crops showed the same growth responses to inorganic fertilization.
• Soil microbial community was affected mainly by soil physico-chemical conditions.
• Archaea and bacteria were the microbial groups most affected by fertility changes.

The structure of soil microbial communities is affected by biotic and abiotic environmental factors, such as plant community composition and soil chemical characteristics, among others. However, little is known about the relative importance of these factors on soil microbial community structure. The objective of this study was to verify which factor, soil chemical characteristics or plant species identity, is more important to the determination of soil microbial community structure. For this, a factorial experiment with four soil chemical conditions and five plant species were set in a greenhouse. After 80 days of cultivation, the rhizospheric soil microbial community structure was accessed by a multiplex T-RFLP, and the mycorrhizal colonization of roots and plant shoot dry mass were estimated. Plant species showed similar growth responses to different soil chemical conditions, but exhibited different patterns in the control of root mycorrhizal colonization. A principal component analysis (PCA) was performed using the T-RFLP data set and showed that soil chemical condition is the main factor defining the structure of soil microbial community. Archaeal and bacterial communities showed to be more sensitive to changes in the soil chemical environment, suggesting a greater importance of these microbial groups in plant adaptation.